This invention relates to an improved process for the production of tertiary-butyl hydroperoxide by direct oxidation of isobutane. More particularly, this invention relates to a continuous oxidation process carried out in a series of reaction zones each maintained as a single dense phase.
Tertiary-butyl hydroperoxide (hereinafter sometimes referred to as TBHP) is a material of commerce having application as a catalyst, as an intiator for free radical-type reactions and as a starting material or intermediate in the production of valuable chemicals such as oxirane compounds and other organic hydroperoxides.
Because of the ready availability and low cost of starting materials, significant effort has been focused in the past specifically on the preparation of TBHP by direct oxidation of isobutane. It is known that this reaction can be conducted in the vapor phase in the presence of an added catalyst, e.g., hydrogen bromide, or in the liquid phase of a vapor-liquid mixture with or without a catalyst, for instance, according to the teachings of Winkler et al (U.S. Pat. No. 2,845,461, and the publication "Liquid Phase Oxidation of Isobutane", Industrial and Engineering Chemistry, vol. 53 (August, 1961), p. 655), Grane et al (U.S. Pat. Nos. 3,478,108 and 3,907,902) and/or Barone et al (U.S. Pat. No. 3,816,540). It has further been found, as described in the commonly-assigned, copending application of E. G. Foster and E. F. Lutz, entitled Oxidation of Isobutane under Supercritical Conditions, Ser. No. 308,631, filed on even date herewith, that the reaction can be carried out in a supercritical reaction mixture at a temperature above the critical temperature of the mixture, at a pressure above the critical pressure of the mixture, and under conditions relating to composition of the mixture. Although the supercritical phase reactoin process offers substantial advantage over the prior art liquid-phase or vapor-phase methods for isobutane oxidation, the production of TBHP by direct oxidation under any of the known processes, an inverse relationship exists between selectivity and conversion in the isobutane oxidation reaction, so that an increase in one is generally obtained only at the expense of a decrease in the other.